Weiner R E
Department of Radiology, Indiana University Medical Center, Indianapolis.
J Nucl Med. 1989 Jan;30(1):70-9.
Physiologic concentrations of ATP stimulate the translocation of gallium-67 (67Ga) from human transferrin (TF) to horse ferritin (HoFE). The mechanism of this translocation was examined. One millimolar ATP did not speed the binding of 67Ga or indium-111 (111In) to HoFE. ATP and pyrophosphate (PPi) at 1 mM, did not form high affinity complexes with 67Ga or 111In. ATP and PPi interacted directly with the [67Ga]TF complex and could within minutes increase the amount of nonprotein-bound 67Ga. Serum HCO3- concentration, 30 mM, prevented the ATP-induced dissociation of 67Ga from TF, whereas intracellular concentrations (0.4 and 5 mM) did not. Using a dialysis technique, ATP also stimulated the translocation of 111In from TF to HoFE; however, this process was much slower than with 67Ga. ATP caused an increase in the nonprotein-bound 111In compared to the control. These results suggest the formation of nonprotein-bound nuclide by these phosphate-containing compounds in a kinetically labile form is important to the translocation mechanism.
生理浓度的三磷酸腺苷（ATP）可刺激镓-67（67Ga）从人转铁蛋白（TF）向马铁蛋白（HoFE）的转运。对这种转运机制进行了研究。1毫摩尔ATP不会加快67Ga或铟-111（111In）与HoFE的结合。1毫摩尔的ATP和焦磷酸（PPi）不会与67Ga或111In形成高亲和力复合物。ATP和PPi直接与[67Ga]TF复合物相互作用，几分钟内就能增加非蛋白结合的67Ga量。血清碳酸氢根（HCO3-）浓度为30毫摩尔时可阻止ATP诱导的67Ga从TF解离，而细胞内浓度（0.4和5毫摩尔）则无此作用。采用透析技术，ATP也可刺激111In从TF向HoFE的转运；然而，这一过程比67Ga的转运慢得多。与对照组相比，ATP使非蛋白结合的111In增加。这些结果表明，这些含磷化合物以动力学不稳定形式形成非蛋白结合的核素对转运机制很重要。
